A Six-Axis Force Sensor with Three-Dimensional Cross-Shape Structure

Abstract

A new six-axis force sensor is described. It has three pairs of elastic elements that are orthogonal to each other and cross at the center of the sensor. Each elastic element consists of a pair of thin parallel plates which is called a parallel plate structure. From the outputs of the strain gauges placed on the elastic elements, the six force components are obtained. This orthogonal structure, which is named the three-dimensional cross-shape structure, has the following merits. (1) The whole characteristic of the sensor is obtainable just by analyzing the force-strain relation of a pair of elastic elements on an axis, maing it simpler to design a sensor for a given specification. (2) The cross-coupling between the strain gauge outputs and the six force components can be made small. (3) It is easy to design a rigid sensor. A prototype sensor has been fabricated and it has ben shown that the measured characteristic coincides with the analysis based on the beam theory ; the cross-coupling is rather small, and the force-strain characteristics in all force directions are uniform. A few design considerations are also given.